This work proposes to develop and test the performance of a low-cost, easy to use, disposable sampler to measure personal exposures to inhalable aerosols in the workplace. To improve the likelihood of future adoption by exposure assessors, the sampler will incorporate a redesign of the inlet cap of the 37-mm sampling cassette, the most commonly used particle sampler in the U.S. The sampler inlet will be designed to sample large particles with efficiency to match the international performance criterion for inhalable aerosol sampling. As such, the sampler will capture particles with the same efficiency as a worker's mouth and nose. This research will: (a) use computational fluid dynamics modeling tools to investigate how inlet geometries affect sampling efficiency, to optimize the sampler inlet, and to estimate an orientation-averaged sampling efficiency for the prototype sampler(s) to compare to the inhalable criterion; (b) investigate the sampling efficiency of the prototype sampler in a low-velocity wind tunnel and a calm-air chamber to quantify accuracy, precision, linearity, and internal losses, in controlled environments; and (c) field test and validate the sampler performance in three manufacturing settings and compare the sampling efficiencies to existing devices. Within the third aim, one of the worksites will examine both exposure and indicators of respiratory inflammation in the workers to examine whether exposures measured with the new inhalable sampler improve the measurements of association of health outcomes. This project addresses multiple NORA sectors (construction, manufacturing, refining, mining, and agriculture) as well as NORA Exposure Assessment cross-sector goals, including developing/improving methods to assess worker exposures to critical occupational agents and validation of these methods to provide and characterize their performance. The long-term outcome of this project includes the advancement of tools to improve exposure assessment evaluations. By increasing the adoption of physiologically-relevant exposure assessment tools, data-driven risk-based exposure limits for hazardous aerosols can be improved to protect worker health.